Virtually all types of human activities generate various types of waste or by-product materials. Many of these materials can be processed to yield substrates that are or may be readily converted into a useful product. Such conversion is desirable for at least three interrelated reasons. First, conversion reduces the load of material that ultimately must be disposed of via traditional waste management methods; second, conversion saves natural resources by more fully utilizing raw products; and third, conversion not only may save energy but may in fact contribute to the supply of energy yielding materials.
Waste has varied forms and characteristics. In terms of the regulation of waste disposal pursuant to federal statutes, rules and regulations, many waste materials are characterized as municipal solid waste pursuant to 42 USC 691 et seq. Other categories of waste materials include animal waste either as it exists in confined animal production facilities or as it may be found in confinement ponds or lagoons. Other wastes from specific industries that may, but are not necessarily included as municipal solid waste, include materials produced during food processing and rendering, wood and timber processing, and chemical and petroleum manufacturing and processing.
Municipal solid waste, more commonly known as trash or garbage, consists of everyday items such as paper, food scraps and yard trimmings that are disposed of and may ultimately end up at landfills. According to the United States Environmental Protection Agency, in 2001 U.S. residents, businesses, and institutions produced more than 229 million tons of municipal solid waste, which amounts to approximately 4.4 pounds of waste per person per day, up from 2.7 pounds per person per day in 1960. Although source reduction, reuse, recycling, and composting can divert portions of municipal solid waste from disposal, a large amount of waste must still must be placed in landfills.
Modern landfills are expensive facilities that require a great deal of funding to build and maintain. Landfills must be built in suitable geological areas away from faults, wetlands, flood plains, or other restricted areas. Typically, liners formed from geomembrane or plastic sheets reinforced with two feet of clay on the bottom and sides of landfills must be installed. In addition, general maintenance including insect and rodent control and ground water monitoring add to landfill costs. Also, closure and postclosure care which includes covering landfills and providing long-term care of closed landfills can further add to costs.
A need currently exists for an improved process for reducing solid waste volume and landfill mass. In particular, a need exists for a process that can reduce the volume of municipal solid waste.